The present invention relates to a machine for removing and fitting wheel tyres for vehicles.
The use of machines, so-called “tyre-changing machines”, is known which allow the fitting and removal of the tyre from the relative rim of a wheel for vehicles.
These tyre-changing machines are used, e.g., in garages to run maintenance or replacement jobs of the rim and/or of the tyre itself.
Generally, known tyre-changing machines comprise a supporting frame to support a gripping and rotation device of the rim of a wheel, and to support a tool-carrying arm having at least one tool able to remove and/or fit the tyre from/onto the rim.
The supporting frame generally comprises a support base of the gripping and rotation device of the rim, commonly consisting of a special self-centering spindle positioned at a predetermined height from the ground.
The supporting frame also comprises a vertical upright which extends from the rear portion of the base and which supports a special tool-carrying arm adjustable along a horizontal direction depending on the specific dimensions of the wheel to be machined.
The tool-carrying arm has a vertically adjustable removing/fitting tool.
The use is also known of at least an auxiliary arm having one or more special bead pressing tools, employable to facilitate the fitting/removal operations onto/from the rim, in particular for lower profile and “runflat” tyres.
For example, a first type of auxiliary arm comprises a horizontal arm hinged to the vertical upright of the supporting frame and rotatable in a vane-like fashion, with which the bead pressing tool is associated vertically movable.
A second type of auxiliary arm comprises a horizontal articulated arm hinged to the vertical upright of the supporting frame and rotatable in a vane-like fashion, with which are associated two or more small tool-carrying arms having separate bead pressing tools (pressers and/or rollers).
In particular, the tool-carrying arms are articulated to the horizontal arm and, conventionally, are able to rotate with respect thereto around a vertical axis coincident with the vertical axis of rotation of the wheel on the spindle.
The horizontal arm or the bead pressing tools themselves are then movable vertically to allow the positioning thereof on the tyre.
In the removal phase, an operator positions and locks the rim of the wheel to be machined on the spindle and performs, by means of a special bead breaking tool, a preliminary phase of removal of the tyre bead from the rim edge.
Subsequently, the operator adjusts the position of the removing/fitting tool according to the specific dimensions of the wheel and positions it in correspondence of a section of the tyre to be lifted above the rim edge, and moves the tool in order to extract a portion of the bead above the rim.
The auxiliary arm is rotated as far as to position the bead pressing tool or tools in correspondence of a portion of the tyre substantially opposite the portion of the tyre lifted portion by means of the removing/fitting tool.
In particular, the pressure applied by the bead pressing tool facilitates the extraction of the tyre bead.
Subsequently, the wheel is partially rotated to allow the extraction of the bead and, during such rotation, each bead pressing tool continues to apply a pressure on the tyre, following the rotation of the wheel.
When the bead pressing tool is located in the proximity of the removing/fitting tool, then the operator raises the bead pressing tool by activating the specific command lever and positions the auxiliary arm in a rest position in order not to hamper the operator's movements during removal of the tyre from the rim.
The complete rotation of the wheel then allows to complete the extraction of the wheel bead above the rim edge.
Similarly, in the fitting phase, an operator positions and locks the wheel rim to be machined on the spindle and positions in a suitable manner the tyre to be fitted on the rim.
Subsequently, the operator adjusts the position of the removing/fitting tool according to the specific dimensions of the wheel and positions it in correspondence of a section of the tyre while pressing it below the rim edge.
The auxiliary arm is rotated as far as to position the bead pressing tool or tools in correspondence of a portion of the tyre, in the proximity of the removing/fitting tool.
In particular, the pressure applied by the bead pressing tool facilitates the insertion of the tyre bead.
Subsequently, the wheel is partially rotated to allow the insertion of the bead and, during such rotation, the bead pressing tool continues to apply a pressure on the tyre, following the rotation of the wheel.
When the bead pressing tool is located in the proximity of the removing/fitting tool, then the operator raises the bead pressing tool by activating the specific command lever and positions the auxiliary arm in a rest position in order not to hamper the operator's movements during the removal of the tyre from the rim.
The complete rotation of the wheel then allows to complete the insertion of the wheel bead below the rim edge.
The known solutions described above do however have some drawbacks.
In particular, subsequently to the use for tyre removing/fitting operations, the auxiliary arm must necessarily be repositioned in the rest position, with the bead pressing tool spaced away from the rim gripping and rotation means, in order not to hamper the operator's movements during the removal or the positioning of the tyre from/onto the rim.
Therefore, this operation inevitably involves an increase in the time required to complete the tyre removing/fitting operations.
The document EP 2,756,969 describes a machine for removing and fitting wheel tyres for vehicles having an auxiliary arm with a bead pressing tool able to facilitate the removing/fitting operations of the tyre from/onto the rim (C).
The auxiliary arm has however a particular conformation and is associated rotatable to the bearing structure of the machine in correspondence of a hinging point arranged below with respect to the resting plane of the rim of a wheel.
The document U.S. Pat. No. 8,783,326 describes a tyre-changing machine comprising an auxiliary arm having several bead pressing tools and automatic means able to control and manage the movement of the bead pressing tools during the removing/fitting operations of a tyre.
However, the machine described in that document does not carry out the automatic repositioning of the auxiliary arm in a rest position, so as to automatically limit the overall dimensions of the auxiliary arm at the end of the removing/fitting operations.